1. Technical Field
This invention relates to an ion exchange membrane electrolyzer. More particularly, the present invention relates to an ion exchange membrane electrolyzer that can hold the gap between the electrodes of the electrolyzer to a predetermined dimension.
2. Description of the Related Art
The voltage required for electrolysis in an electrolyzer for electrolysis of aqueous solution depends on various factors. Above all, the gap between the anode and the cathode of the electrolyzer affects significantly to the electrolyzer voltage. It is a common practice to reduce the energy consumption necessary for electrolysis by reducing the gap between the electrodes and hence the eloectrolyzer voltage.
In ion exchange membrane electrolyzers that operate for electrolysis of brine, the electrolyzer voltage is reduced by arranging the trio of the anode, the ion exchange membrane and the cathode in a condition where they are held in tight contact with each other. However, in a large electrolyzer where the electrodes extend over an area of several square meters and the anode and the cathode are rigid members, it is difficult to hold them in tight contact with the ion exchange membrane and keep the inter-electrode gap to a predetermined small distance.
Thus, there have been proposed electrolyzers where a flexible member is used for either the anode or the cathode to make the inter-electrode gap adjustable.
Various electrolyzers using a flexible member as means for reducing the inter-electrode gap have been proposed. More specifically, electrodes formed by arranging a flexible member made of woven fabric, unwoven fabric or a network of fine metal threads on a porous electrode substrate are known.
Since the flexible members of such electrodes are formed by using fine metal threads, they can give rise to problems such as that the electrode is partially deformed to make the inter-electrode gap uneven when it is pressed excessively by the counter-pressure from the other electrode and that some of the fine metal threads stick in the ion exchange membrane.
Japanese Patent No. 3501453 proposes an electrolyzer in which the electrode chamber bulkhead side and the electrode are electrically conductively connected by means of a large number of plate-shaped leaf springs.
FIG. 11A of the accompanying drawings is a schematic perspective view of known leaf springs that can be used in an electrolyzer. FIG. 11B of the accompanying drawings is a schematic cross sectional horizontal view of the electrode chamber of an electrolyzer comprising leaf springs as shown in FIG. 11A.
A plurality of pairs of obliquely standing leaf springs 12, each having a profile of a tooth of a comb, are fitted to a plate-shaped leaf spring holding member 11. A total of three pairs of teeth-like leaf springs are shown in FIG. 11B. The teeth-like leaf springs 12 of each pair extend in opposite directions to show an inter-digital arrangement as a whole.
Each leaf spring 12 has an electrode-touching section 15 formed by bending the front end which touches the electrode toward the leaf spring holding member 11 so as to extend substantially in parallel with the leaf spring holding member 11. An electrically conductive connection is established as the electrode-touching section 15 touches an electrode.
As shown in FIG. 11B, electrode touching sections 15 that extend substantially in parallel with the leaf spring holding member 12 are arranged at the cathode side of a cathode chamber 9 so that the leaf springs 12 touch the cathode 8 as the gap between the cathode 8 and the leaf spring holding member 11 is reduced.
However, if the cathode 8 is pressed to a large extent in the assembling process or the pressure rises abnormally to invert the pressure relationship between the anode chamber 6 and the cathode chamber 9 in favor of the anode side while the electrolyzer is in a preparation stage for operation and the gap between the cathode 8 and the cathode chamber bulkheard 7 is reduced, some of the leaf springs 12 can be plastically deformed to lose their resiliency once the gap is reduced beyond a certain limit. Particularly, the cathode chamber is normally made of plates of nickel that is a poorly resilient metal material so that, once its resiliency is lost, its function of adjusting the inter-polar distance by its resiliency is also lost to give rise to a problem that the predetermined inter-polar distance is no longer maintained.
The present invention relates to an electrolyzer in which electrodes and a collector are bound to each other by a flexible conducting member and the object of the present invention is to provide an electrolyzer that comprises electrodes having a large area and the surfaces of the electrodes can be held smooth so that neither of the electrodes may not be moved in any direction and no excessive pressure is applied to the surfaces of the ion exchange membrane by the flexible conducting member and that the flexible conductive member retains its resiliency if the pressure relationship between the anode chamber and the cathode chamber is inverted by abnormally high pressure in the electrolyzer.